DC-52 is a substance produced by Streptomyces melanovinaceus DO-52, FERM BP-654, which was transferred on Nov. 12, 1984 from FERM P-5911 deposited on Mar. 14, 1981, and has the following structure and an antitumor activity upon leukemia P-388 ascites type tumor cells (Japanese Published Unexamined Patent Application No. 170189/1982). ##STR1##
However, DC-52 is unstable and liable to decompose during the purification and powdering (for example, freeze-drying), and DC-52 of high purity can not be obtained. The decomposition proceeds even during the preservation.